Briggs and Strat Engine won’t turn over ?

Liammcgee123

I have a 2005 mower with 690 hours on it. It is a Briggs and Stratton 17.5Hp engine.
For over a year It can be difficult to start the engine ... You turn the key , it goes once over but can’t get past a point ! It’s not the battery or Starter .
I adjusted the valves but still no joy so I thought it must be the cam shaft ! I opened the engine and everything is working very well with no wear . Anyone any ideas of what the problem could be ? Driving me mad !

_Brian

I’d wonder about the timing.

emeldc

Assuming it's a single cylinder have you tried cranking it with the plug removed. Could the piston be hitting the valve?

blackbox

If it's not the battery or starter, could it be the solenoid?

If you are fairly competent with engines, try connecting a jump lead from the battery + and holding the other end to the starter + connection to bypass the solenoid. It will spark loads as you hold it to the starter, so protect your eyes, but if the problem was the solenoid this should spin it.

Don't try this if you aren't familiar with batteries and electrics as potentially you could start a fire or injure yourself.

CJhaughey

If the engine won't swing over on the compression stroke, it must be either the starter or the battery. How have you verified that the battery and starter are good?

Batteries can appear to be good when tested but under load won't give sufficient amperage to turn the starter with authority.
Starters can spin freely when they are under no load but once loaded they are weak.